C-16, C-19 and B-15A icebergs in the Ross Sea, Antarctica

Credit:

Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

The emergence of Antarctica from months of total darkness reveals the location of new icebergs that calved off the Ross Ice Shelf during the long winter. Some of the icebergs shown in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images of Antarctica are on the move. Along the western portion of the image lie the Trans-Antarctic Mountains. In the center is the Ross Sea. Banked up against the Antarctic coastline is the vast Ross Ice Shelf (bottom right). Numerous large icebergs have calved off the shelf and are visible in this series of images

B-15a (southeast of center in these images, pointing out to sea) calved off the eastern portion of the shelf in March 2000 and drifted westward before apparently becoming anchored at its southern end near Ross Island. (Tucked between B-15a and Ross Island is a smaller berg produced during the same calving event that gave rise to B-15. This berg is designated C-16). Scientists have watched B-15 rock like a pendulum, but so far it has not broken free of its moorings. When the B-15 "mother" iceberg broke free of the shelf, it was one of the largest icebergs ever observed by scientists. The original length was roughly one-third of the total length of the ice shelf’s front—about 300 kilometers by 37 kilometers, or 180 miles by 22 miles.

When this series of images begins on September 22, 2002, the C-19 iceberg is perpendicular to the northern end of B-15, but over the next month, the berg moves out to sea. C-19 calved off the Ross Ice Shelf in May 2002. With calving of the C-19 berg, scientists now think the Ross Ice Shelf, which had been growing slowly over the past century, has returned to the size it was when the first European explorers reached Antarctica in the early 1900s.

Scientists believe these large bergs are part of the natural cycle of the shelf, and unlike the collapse of the Larsen Ice Shelf on the other side of the continent, are probably not due to rising ocean temperatures. The shelf forms as snowfall on the continent slides slowly off the sides of Antarctica and pushes out to sea. While a large portion of the shelf is underwater, it is still afloat (not anchored to the bottom of the ocean), and eventually, the shelf collapses under it’s own massive weight, producing ice bergs.

Images & Animations

File

File Dimensions

Note: Often times, due to the size, browsers have a difficult time opening and displaying images. If you experiece an error when clicking on an image link, please try directly downloading the image (using a right click, save as method) to view it locally.